Geston5 mg

Geston is a synthetic oral progestogen used, under medical supervision, for progestogenic support in pregnancy. Its use should always be guided and monitored by a physician.

Established / Labeled Use

• Threatened miscarriage: Geston is used as supportive therapy in threatened miscarriage (bleeding or symptoms suggesting risk of pregnancy loss in early pregnancy), particularly where progesterone deficiency is suspected.
• Habitual (recurrent) miscarriage: Geston is used for prevention of recurrent pregnancy loss attributed to progesterone deficiency, as part of an overall management plan.

Evidence Note

The strength of evidence supporting Geston for these pregnancy indications varies across regulatory bodies and clinical guidelines, and some systematic reviews have found limited or inconsistent benefit in unselected patients with recurrent miscarriage. Geston remains a labeled and commonly prescribed option in several markets, including Bangladesh, but should be used only after a physician has assessed the likelihood of progesterone deficiency and confirmed there is no other explanation for pregnancy loss.

Each tablet typically contains Allylestrenol as the active ingredient, most commonly available as 5 mg oral tablets. Strength and available pack sizes may vary by manufacturer and market; refer to the specific product label for exact composition.

Geston is a synthetic progestogen (a derivative of 19-nortestosterone) taken by mouth. It is chemically distinct from many other progestins in that it is largely devoid of estrogenic, androgenic, and significant anabolic activity, which makes it suitable for use during pregnancy when progestogenic support is required.

Geston is used specifically for progesterone-deficiency-related pregnancy complications, namely threatened and habitual (recurrent) miscarriage, and is not used as a general-purpose hormonal or contraceptive agent.

Geston belongs to the therapeutic class of progestogens (synthetic progesterone derivatives), specifically an orally active progesterone receptor agonist used for progestogenic support in pregnancy.

Mechanism of Action

Allylestrenol acts as an agonist at the progesterone receptor. By binding to and activating progesterone receptors in the endometrium and myometrium, it supports the secretory transformation of the endometrium, helps maintain uterine quiescence, and reduces uterine contractility, thereby supporting continuation of pregnancy when progesterone deficiency contributes to the risk of miscarriage.

Unlike many other 19-nortestosterone-derived progestins, Allylestrenol has minimal estrogenic, androgenic, or anabolic activity at therapeutic doses, and does not appear to have significant glucocorticoid or antimineralocorticoid activity.

Pharmacokinetics

• Absorption: Well absorbed after oral administration; peak plasma concentrations are typically reached within a few hours.
• Metabolism: Hepatic, involving reduction, hydroxylation, and conjugation; the CYP3A4 enzyme pathway is involved in its metabolism.
• Elimination half-life: Approximately 10 hours.
• Excretion: Primarily via urine, mostly within a few days of dosing.

Geston is administered orally. Tablets should be swallowed whole with a glass of water, at regular intervals as prescribed, with or without food. Consistency in timing helps maintain steady drug levels. Do not double the dose if a dose is missed; take it as soon as remembered unless it is close to the next scheduled dose.

Geston is metabolized in the liver via pathways involving the CYP3A4 enzyme, so drugs that induce or inhibit this enzyme may alter its blood levels and effectiveness.

• CYP3A4 inducers (e.g., rifampicin, phenytoin, carbamazepine, phenobarbital, St. John's Wort): may accelerate metabolism of Geston, potentially reducing its effectiveness. Dose adjustment or closer monitoring may be needed if co-administered.
• CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, certain macrolide antibiotics, protease inhibitors): may reduce metabolism of Geston, potentially increasing its levels and the risk of side effects.

Beyond these CYP3A4-mediated interactions, no other extensively documented, clinically significant systemic drug interactions are established for Geston, reflecting its limited off-target hormonal activity. Always inform the physician of all medicines, supplements, and herbal products being used.

Geston is generally well tolerated at labeled doses. Reported side effects are usually mild and may include:

• Mild gastrointestinal upset (nausea, bloating)
• Breast tenderness
• Mild fluid retention (progestogenic effect)
• Headache or dizziness (uncommon)
• Skin rash (rare, may indicate hypersensitivity — see Contraindications)

Serious hormone-related side effects such as androgenic or estrogenic effects are not typically seen with Geston due to its favorable receptor selectivity. Report any severe or persistent symptoms to the prescribing physician promptly.

Pregnancy: Geston is specifically indicated, under medical supervision, for progestogenic support during pregnancy in the setting of threatened or habitual miscarriage due to suspected progesterone deficiency. It should be used only after evaluation by a physician confirms this is an appropriate indication, and treatment should be monitored throughout the pregnancy. This differs from most other medicines, where pregnancy use is generally discouraged — here, physician-guided use during pregnancy is the primary purpose of the drug. Geston is not intended for indications unrelated to pregnancy support.

Lactation: Data on Geston use during breastfeeding are limited. Since its indication is specific to pregnancy support, it is not typically continued into the lactation period. If use during breastfeeding is being considered for any reason, a physician should be consulted to weigh potential benefits and risks to the infant.

Geston should be used only under medical supervision, with regular monitoring during pregnancy, since it is specifically indicated for a pregnancy-related condition.

• A thorough evaluation to rule out other causes of vaginal bleeding or pregnancy loss (e.g., ectopic pregnancy, infection, chromosomal abnormality) should be performed before starting Geston, as it is intended for progesterone-deficiency-related causes specifically.
• Treatment should not be continued beyond the period for which the pregnancy-support indication applies, and should be reassessed regularly by the treating physician.
• Use with caution in patients with a history of hepatic impairment, thromboembolic risk factors, or hormone-sensitive conditions (see Contraindications for absolute restrictions).
• If undiagnosed vaginal bleeding occurs during treatment, the physician should be informed promptly for reassessment.

Specific data on Geston overdose are limited. In the event of a suspected overdose, exaggerated progestogenic effects such as nausea, vomiting, or breast tenderness may occur. There is no specific antidote.

If an overdose of Geston is suspected, seek immediate medical attention or contact a poison control center/emergency services right away. Do not attempt to manage a suspected overdose at home without professional guidance.

Store at room temperature (below 30°C), away from light and moisture. Keep out of reach of children.

Pregnant Women

Geston is specifically used in pregnancy for threatened or habitual miscarriage under physician supervision, as described in Indications and Pregnancy and Lactation.

Breastfeeding Women

Not typically used during lactation, as its indication is pregnancy-specific; see Pregnancy and Lactation.

Pediatric Use

Geston is not indicated for use in children; safety and efficacy in the pediatric population have not been established, and it has no approved pediatric indication.

Elderly

Not applicable, as Geston is used exclusively in women during pregnancy.

Hepatic Impairment

Geston is contraindicated in severe hepatic impairment (see Contraindications); use with caution and physician guidance in milder hepatic dysfunction.

Renal Impairment

No well-established dose adjustment is required for renal impairment, but use should still be under physician supervision.

Duration of Geston treatment is individualized by the treating physician. For threatened miscarriage, it is generally continued until symptoms resolve. For habitual (recurrent) miscarriage, it is often continued from early pregnancy through the gestational period during which previous losses occurred (commonly up to approximately 20-28 weeks), as determined by the physician based on clinical history and response.

Allylestrenol is classified as a synthetic progestogen (19-nortestosterone-derived progesterone receptor agonist) used for progestogenic support in pregnancy.

Allylestrenol works by binding to and activating progesterone receptors in the uterus, supporting endometrial and myometrial changes that favor maintenance of pregnancy and reducing uterine contractility, without significant estrogenic, androgenic, or anabolic activity.

Geston has no approved use in children. It is exclusively indicated for adult women during pregnancy for progestogenic support, and safety and efficacy in pediatric patients have not been established.